What were Aristotle's three forms of government?

Aristotle actually delineated SIX forms : there are three pairs of congruent governments :

1. A state with only one ruler is either a monarchy or a tyranny
2. A state with several rulers is either an aristocracy or an oligarchy
3. A state in which mob rule or a democracy.

A "polity" was used by Aristotle to describe a democracy kept from excesses by the influence of the wealthy. In this regard, it is similar to the modern democracies that have a titular ruler. Aristotle also stated that all governments are inherently unstable and tend to "cycle" through the various forms.

A Clarification

Aristotle's 3 classifications of government are

• Monarchy (rule by one), (President)
• Aristocracy (power of the best people/rich, Senate)
• Democracy (people power/mob rule, House of Representative)

He said that Monarchy tended to degrade to Tyranny, Aristocracy to Oligarchy (rule of the few) and Democracy to Ochlocracy (mob power).

(see graphic link)